shelve: move commitfunc creation to a separate function
Special commitfuncs are created as closures at least twice in shelve's
code and one time special commitfunc is used within another closure.
They all serve very specific purposes like temporarily tweak some
configuration or enable editor, etc. This is not immediately important
to someone reading shelve code, so I think moving this logic to a separate
function is a good idea.
# commandserver.py - communicate with Mercurial's API over a pipe
#
# Copyright Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import errno
import gc
import os
import random
import select
import signal
import socket
import struct
import sys
import traceback
from .i18n import _
from . import (
encoding,
error,
util,
)
logfile = None
def log(*args):
if not logfile:
return
for a in args:
logfile.write(str(a))
logfile.flush()
class channeledoutput(object):
"""
Write data to out in the following format:
data length (unsigned int),
data
"""
def __init__(self, out, channel):
self.out = out
self.channel = channel
@property
def name(self):
return '<%c-channel>' % self.channel
def write(self, data):
if not data:
return
# single write() to guarantee the same atomicity as the underlying file
self.out.write(struct.pack('>cI', self.channel, len(data)) + data)
self.out.flush()
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.out, attr)
class channeledinput(object):
"""
Read data from in_.
Requests for input are written to out in the following format:
channel identifier - 'I' for plain input, 'L' line based (1 byte)
how many bytes to send at most (unsigned int),
The client replies with:
data length (unsigned int), 0 meaning EOF
data
"""
maxchunksize = 4 * 1024
def __init__(self, in_, out, channel):
self.in_ = in_
self.out = out
self.channel = channel
@property
def name(self):
return '<%c-channel>' % self.channel
def read(self, size=-1):
if size < 0:
# if we need to consume all the clients input, ask for 4k chunks
# so the pipe doesn't fill up risking a deadlock
size = self.maxchunksize
s = self._read(size, self.channel)
buf = s
while s:
s = self._read(size, self.channel)
buf += s
return buf
else:
return self._read(size, self.channel)
def _read(self, size, channel):
if not size:
return ''
assert size > 0
# tell the client we need at most size bytes
self.out.write(struct.pack('>cI', channel, size))
self.out.flush()
length = self.in_.read(4)
length = struct.unpack('>I', length)[0]
if not length:
return ''
else:
return self.in_.read(length)
def readline(self, size=-1):
if size < 0:
size = self.maxchunksize
s = self._read(size, 'L')
buf = s
# keep asking for more until there's either no more or
# we got a full line
while s and s[-1] != '\n':
s = self._read(size, 'L')
buf += s
return buf
else:
return self._read(size, 'L')
def __iter__(self):
return self
def next(self):
l = self.readline()
if not l:
raise StopIteration
return l
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.in_, attr)
class server(object):
"""
Listens for commands on fin, runs them and writes the output on a channel
based stream to fout.
"""
def __init__(self, ui, repo, fin, fout):
self.cwd = os.getcwd()
# developer config: cmdserver.log
logpath = ui.config("cmdserver", "log", None)
if logpath:
global logfile
if logpath == '-':
# write log on a special 'd' (debug) channel
logfile = channeledoutput(fout, 'd')
else:
logfile = open(logpath, 'a')
if repo:
# the ui here is really the repo ui so take its baseui so we don't
# end up with its local configuration
self.ui = repo.baseui
self.repo = repo
self.repoui = repo.ui
else:
self.ui = ui
self.repo = self.repoui = None
self.cerr = channeledoutput(fout, 'e')
self.cout = channeledoutput(fout, 'o')
self.cin = channeledinput(fin, fout, 'I')
self.cresult = channeledoutput(fout, 'r')
self.client = fin
def cleanup(self):
"""release and restore resources taken during server session"""
pass
def _read(self, size):
if not size:
return ''
data = self.client.read(size)
# is the other end closed?
if not data:
raise EOFError
return data
def _readstr(self):
"""read a string from the channel
format:
data length (uint32), data
"""
length = struct.unpack('>I', self._read(4))[0]
if not length:
return ''
return self._read(length)
def _readlist(self):
"""read a list of NULL separated strings from the channel"""
s = self._readstr()
if s:
return s.split('\0')
else:
return []
def runcommand(self):
""" reads a list of \0 terminated arguments, executes
and writes the return code to the result channel """
from . import dispatch # avoid cycle
args = self._readlist()
# copy the uis so changes (e.g. --config or --verbose) don't
# persist between requests
copiedui = self.ui.copy()
uis = [copiedui]
if self.repo:
self.repo.baseui = copiedui
# clone ui without using ui.copy because this is protected
repoui = self.repoui.__class__(self.repoui)
repoui.copy = copiedui.copy # redo copy protection
uis.append(repoui)
self.repo.ui = self.repo.dirstate._ui = repoui
self.repo.invalidateall()
for ui in uis:
ui.resetstate()
# any kind of interaction must use server channels, but chg may
# replace channels by fully functional tty files. so nontty is
# enforced only if cin is a channel.
if not util.safehasattr(self.cin, 'fileno'):
ui.setconfig('ui', 'nontty', 'true', 'commandserver')
req = dispatch.request(args[:], copiedui, self.repo, self.cin,
self.cout, self.cerr)
ret = (dispatch.dispatch(req) or 0) & 255 # might return None
# restore old cwd
if '--cwd' in args:
os.chdir(self.cwd)
self.cresult.write(struct.pack('>i', int(ret)))
def getencoding(self):
""" writes the current encoding to the result channel """
self.cresult.write(encoding.encoding)
def serveone(self):
cmd = self.client.readline()[:-1]
if cmd:
handler = self.capabilities.get(cmd)
if handler:
handler(self)
else:
# clients are expected to check what commands are supported by
# looking at the servers capabilities
raise error.Abort(_('unknown command %s') % cmd)
return cmd != ''
capabilities = {'runcommand' : runcommand,
'getencoding' : getencoding}
def serve(self):
hellomsg = 'capabilities: ' + ' '.join(sorted(self.capabilities))
hellomsg += '\n'
hellomsg += 'encoding: ' + encoding.encoding
hellomsg += '\n'
hellomsg += 'pid: %d' % util.getpid()
if util.safehasattr(os, 'getpgid'):
hellomsg += '\n'
hellomsg += 'pgid: %d' % os.getpgid(0)
# write the hello msg in -one- chunk
self.cout.write(hellomsg)
try:
while self.serveone():
pass
except EOFError:
# we'll get here if the client disconnected while we were reading
# its request
return 1
return 0
def _protectio(ui):
""" duplicates streams and redirect original to null if ui uses stdio """
ui.flush()
newfiles = []
nullfd = os.open(os.devnull, os.O_RDWR)
for f, sysf, mode in [(ui.fin, sys.stdin, 'rb'),
(ui.fout, sys.stdout, 'wb')]:
if f is sysf:
newfd = os.dup(f.fileno())
os.dup2(nullfd, f.fileno())
f = os.fdopen(newfd, mode)
newfiles.append(f)
os.close(nullfd)
return tuple(newfiles)
def _restoreio(ui, fin, fout):
""" restores streams from duplicated ones """
ui.flush()
for f, uif in [(fin, ui.fin), (fout, ui.fout)]:
if f is not uif:
os.dup2(f.fileno(), uif.fileno())
f.close()
class pipeservice(object):
def __init__(self, ui, repo, opts):
self.ui = ui
self.repo = repo
def init(self):
pass
def run(self):
ui = self.ui
# redirect stdio to null device so that broken extensions or in-process
# hooks will never cause corruption of channel protocol.
fin, fout = _protectio(ui)
try:
sv = server(ui, self.repo, fin, fout)
return sv.serve()
finally:
sv.cleanup()
_restoreio(ui, fin, fout)
def _initworkerprocess():
# use a different process group from the master process, in order to:
# 1. make the current process group no longer "orphaned" (because the
# parent of this process is in a different process group while
# remains in a same session)
# according to POSIX 2.2.2.52, orphaned process group will ignore
# terminal-generated stop signals like SIGTSTP (Ctrl+Z), which will
# cause trouble for things like ncurses.
# 2. the client can use kill(-pgid, sig) to simulate terminal-generated
# SIGINT (Ctrl+C) and process-exit-generated SIGHUP. our child
# processes like ssh will be killed properly, without affecting
# unrelated processes.
os.setpgid(0, 0)
# change random state otherwise forked request handlers would have a
# same state inherited from parent.
random.seed()
def _serverequest(ui, repo, conn, createcmdserver):
fin = conn.makefile('rb')
fout = conn.makefile('wb')
sv = None
try:
sv = createcmdserver(repo, conn, fin, fout)
try:
sv.serve()
# handle exceptions that may be raised by command server. most of
# known exceptions are caught by dispatch.
except error.Abort as inst:
ui.warn(_('abort: %s\n') % inst)
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
except KeyboardInterrupt:
pass
finally:
sv.cleanup()
except: # re-raises
# also write traceback to error channel. otherwise client cannot
# see it because it is written to server's stderr by default.
if sv:
cerr = sv.cerr
else:
cerr = channeledoutput(fout, 'e')
traceback.print_exc(file=cerr)
raise
finally:
fin.close()
try:
fout.close() # implicit flush() may cause another EPIPE
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
class unixservicehandler(object):
"""Set of pluggable operations for unix-mode services
Almost all methods except for createcmdserver() are called in the main
process. You can't pass mutable resource back from createcmdserver().
"""
pollinterval = None
def __init__(self, ui):
self.ui = ui
def bindsocket(self, sock, address):
util.bindunixsocket(sock, address)
def unlinksocket(self, address):
os.unlink(address)
def printbanner(self, address):
self.ui.status(_('listening at %s\n') % address)
self.ui.flush() # avoid buffering of status message
def shouldexit(self):
"""True if server should shut down; checked per pollinterval"""
return False
def newconnection(self):
"""Called when main process notices new connection"""
pass
def createcmdserver(self, repo, conn, fin, fout):
"""Create new command server instance; called in the process that
serves for the current connection"""
return server(self.ui, repo, fin, fout)
class unixforkingservice(object):
"""
Listens on unix domain socket and forks server per connection
"""
def __init__(self, ui, repo, opts, handler=None):
self.ui = ui
self.repo = repo
self.address = opts['address']
if not util.safehasattr(socket, 'AF_UNIX'):
raise error.Abort(_('unsupported platform'))
if not self.address:
raise error.Abort(_('no socket path specified with --address'))
self._servicehandler = handler or unixservicehandler(ui)
self._sock = None
self._oldsigchldhandler = None
self._workerpids = set() # updated by signal handler; do not iterate
def init(self):
self._sock = socket.socket(socket.AF_UNIX)
self._servicehandler.bindsocket(self._sock, self.address)
self._sock.listen(socket.SOMAXCONN)
o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
self._oldsigchldhandler = o
self._servicehandler.printbanner(self.address)
def _cleanup(self):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
self._sock.close()
self._servicehandler.unlinksocket(self.address)
# don't kill child processes as they have active clients, just wait
self._reapworkers(0)
def run(self):
try:
self._mainloop()
finally:
self._cleanup()
def _mainloop(self):
h = self._servicehandler
while not h.shouldexit():
try:
ready = select.select([self._sock], [], [], h.pollinterval)[0]
if not ready:
continue
conn, _addr = self._sock.accept()
except (select.error, socket.error) as inst:
if inst.args[0] == errno.EINTR:
continue
raise
pid = os.fork()
if pid:
try:
self.ui.debug('forked worker process (pid=%d)\n' % pid)
self._workerpids.add(pid)
h.newconnection()
finally:
conn.close() # release handle in parent process
else:
try:
self._runworker(conn)
conn.close()
os._exit(0)
except: # never return, hence no re-raises
try:
self.ui.traceback(force=True)
finally:
os._exit(255)
def _sigchldhandler(self, signal, frame):
self._reapworkers(os.WNOHANG)
def _reapworkers(self, options):
while self._workerpids:
try:
pid, _status = os.waitpid(-1, options)
except OSError as inst:
if inst.errno == errno.EINTR:
continue
if inst.errno != errno.ECHILD:
raise
# no child processes at all (reaped by other waitpid()?)
self._workerpids.clear()
return
if pid == 0:
# no waitable child processes
return
self.ui.debug('worker process exited (pid=%d)\n' % pid)
self._workerpids.discard(pid)
def _runworker(self, conn):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
_initworkerprocess()
h = self._servicehandler
try:
_serverequest(self.ui, self.repo, conn, h.createcmdserver)
finally:
gc.collect() # trigger __del__ since worker process uses os._exit
_servicemap = {
'pipe': pipeservice,
'unix': unixforkingservice,
}
def createservice(ui, repo, opts):
mode = opts['cmdserver']
try:
return _servicemap[mode](ui, repo, opts)
except KeyError:
raise error.Abort(_('unknown mode %s') % mode)